CN102381707A

CN102381707A - Technology for preparing ultrafine WC powder containing grain growth inhibitors Cr and V

Info

Publication number: CN102381707A
Application number: CN2011102171754A
Authority: CN
Inventors: 王平; 王子仪; 郑峰
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-08-01
Filing date: 2011-08-01
Publication date: 2012-03-21

Abstract

Due to favorable high-temperature strength, toughness and wear-resistance, submicron and ultrafine WC-Co hard alloy products take up high-end markets of tools and dies, mining, machinofacture, infrastructure construction and the like for a long time, and are widely applied in a global range. The invention discloses a production technology and process for preparing ultrafine WC powder by using ammonium paratungstate (APT) through direct reduction carbonization according to years of researches. By improving a powder preparation process and adopting a special method to add a proper amount of trace elements, the technology disclosed by the invention can be used to produce ultrafine WC powder containing grain growth inhibitors Cr and V, and a corresponding high-grade hard alloy product.

Description

The ultrafine WC powder technology of preparing that contains grain growth inhibitor Cr and V

Technical field

The present invention relates to a kind of through mix trace element as additive to suppress grain growth, use the direct reduction and carbonization of APT and prepare the production technology and the technology of ultrafine WC powder.

Preparation ultrafine WC powder of the present invention uses an amount of micro-Cr and V as grain growth inhibitor.How adding the control of trace element and each content of elements is one of core technology of the present invention.

The ultrafine WC powder that contains grain growth inhibitor Cr and V that the present invention relates to can be used for producing the hart metal product of superfine crystal particle.

Background technology

SinceSub-micro thin with the appearance of superfine WC-Co hart metal product since; Because it has H.T. and high-wearing feature and higher hot strength; This series products more and more receives the attention of each industrial state, and aspects such as the mining in the whole world, machinofacture, infrastructure construction obtain increasing application.The superfine WC-Co hart metal product at first is developed production in developed countries such as Sweden, the U.S., Germany, Japan, main service aid market.China develops since the production that the later stage seventies in last century just adds this series products, and existing more than 50 trade mark belongs to the superfine WC-Co wimet both at home and abroad at present.

In order to make the ultra-fine grain wimet of excellent performance, to prepare the WC powder of submicron order earlier.Traditional method of producing submicron WC powder adopts low temperature hydrogen also originally to prepare ultrafine tungsten powder, then with carbon mixing carbonization.This method exists several difficult: 1) reduction phase is difficult to control tungsten powder particle-size and grows up; 2) storage of ultrafine tungsten powder and hard transportation; 3) WC particle can be grown up etc. in the carbonization process.

There are two gordian techniquies in production ultrafine WC powder, and the one, control carbon content, the 2nd, the granularity of control WC.As everyone knows, how to avoid the key that water-gas reaction is the control carbon content.For this reason, we consider to use nitrogen protection, and promptly the reduction with carbon carbonization prepares the ultrafine WC powder in nitrogen.

Control size is another key of preparation ultrafine WC powder.There is research to point out that the activity of original Tungsten oxide 99.999 is high more, can significantly reduces carbonization temperature.With the raw material of oxide compound, prepare tungsten powder with the quadrol tungstate as preparation ultrafine WC powder.The quadrol tungstate has autoreduction property, and degradation production has active high and good dispersivity and residual carbon amount advantages of higher.Tungsten powder specific surface area with the preparation of quadrol tungstate can reach 20-30m ²/ g, and its aggregate keeps the pseudo-crystalline form attitude identical with raw material basically.The growing up of WC particle is to be assembled by the sintering under the high temperature grows up and grow up and cause in the inhomogeneous part of causing of granularity.Influencing the principal element that WC particle grows up has: original tungsten powder particle-size, carbonization temperature and time, and the size of the kind of suppressor factor and amount.Mix trace element as additive to suppress grain growth, be the effective ways of producing the ultrafine WC powder.Early stage research shows that IV, V, VI family refractory carbide and refractory metal can stop the inhomogeneous of WC grain to grow up in the adding periodictable; The maximum carbide of dissolving is VC in Co, secondly is Mo ₂C, Cr ₃C ₂, NbC, TaC, TiC, ZrC and HfC.The effect that stops WC grain to be grown up is directly proportional with its solubleness in Co, i.e. V>Mo>Cr>Nb>Ta>Ti>Zr>Hf.When addition reached capacity in the Co liquid phase, its effect that suppresses grain growth was maximum.

Summary of the invention

To the production status of present domestic wimet, we select to use the direct reduction and carbonization of APT to prepare the production technology and the technology of ultrafine WC powder through making great efforts for many years.Through improving flouring technology, utilize special methods successfully to add an amount of trace element, develop the ultrafine WC powder that contains grain growth inhibitor Cr and V that can be used for producing high grade hart metal product.The present invention accomplishes through a large amount of experimental studies; CEMENTED CARBIDE PRODUCTION producer (referring to example 1) in the zhuzhou, hunan province; Zhuzhou, hunan province company (referring to example 2), Changsha, Hunan company business enterprise expands such as (referring to examples 3) uses, and obtains tangible economic benefit.

This invention relates to a kind of technology of preparing that is used to produce the ultrafine WC powder that contains grain growth inhibitor Cr and V of ultra-fine cemented carbide, and following characteristics are arranged:

1) according to the mechanism research of growing up of alloy phase diagram analysis and particle,, suitable chemical ingredients, carbon content and grain growth inhibitor content have been confirmed through a large amount of powder process test and research of wimet compacting sintering mechanism;

2) can generate volatile components such as the H that much has reductibility during the thermolysis of quadrol tungstate ₂, NH ₃, CH ₄, C ₂H ₂Deng.These components at high temperature are decomposed to form the uniform uncombined carbon of distribution disperse, and the autoreduction process of (600-700 ℃) plays a decisive role in the high-temperature zone to tungstate.Adopt this method, high, active big through optimizing the doped tungsten oxide specific surface area for preparing after the technology;

3) adds in the WC powder through special methods and regulate and control micro-(grain growth inhibitor Cr and V); The grain growth inhibitor that adds is with VC or Cr ₇C ₃And Cr ₃C ₂Be present in mutually in the WC powder;

4) adding grain growth inhibitor at preparatory phase has many advantages, comprises the grain growth inhibitor disperse is distributed in the powder, and refinement calcination product is Tungsten oxide 99.999 at a low price, in direct reduction and carbonization process, suppresses the WC particle and grows up;

5) directly the suitable process conditions of reduction and carbonization is: at first produce high reactivity with the quadrol tungstate, the Tungsten oxide 99.999 of high-specific surface area; Use this Tungsten oxide 99.999 to join the direct reduction and carbonization of carbon then as raw material; Suitable process conditions is: 1000 ℃/2h/N ₂+ 1100 ℃/1h/H ₂

6) the used prices of raw and semifnished materials of technology of preparing of the ultrafine WC powder that contains grain growth inhibitor Cr and V of the present invention are cheap, in liberal supply.Simple, the control easily of the ultrafine WC powder preparation technique that contains grain growth inhibitor Cr and V; Has tangible economic benefit.

The key technical indexes that contains the ultrafine WC powder of grain growth inhibitor Cr and V of the present invention comprises that carbon content and powder granularity (BET-S) value are as shown in table 1.

Table 1 WC powder carbon content and BET-S value

Numbering	0L	3L	6L	10L	6F	6L ₁
							Carbon content (m%)	6.084	5.426	6.851	6.996	6.210	5.440
BET-S value (m ²/g)	11.46	12.22	13.84	14.97	17.04	10.47

Annotate: (1000 ℃/2h/N ₂)+(1100 ℃/1h/H ₂)

The production unit that contains the ultrafine WC powder of grain growth inhibitor Cr and V comprises:

1) conversion unit;

2) GK-2B high temperature dispersing furnace;

3) molybdenum wire furnace;

4) graphite burns boat;

5) baking oven;

6) 101 shaped steel iron carbometers;

7) SE-03 type surface apertures appearance;

8) Vacuum Packaging Machine.

Description of drawings

Fig. 1 is the concrete technological process of production synoptic diagram of the production of the present invention ultrafine WC powder that contains grain growth inhibitor Cr and V.

Embodiment

To domestic and international active demand to the ultrafine WC powder; Through TE for many years; We develop the technology of preparing of the ultrafine WC powder that contains grain growth inhibitor Cr and V, and the application of succeeding of several at home families hart metal product and powder metallurgy product manufacturer.Ultrafine WC powder and a certain proportion of Co powder uniform mixing that at first will contain grain growth inhibitor Cr and V, the blank that is pressed into definite shape then obtain having the hart metal product of superfine crystal particle after through the high-temperature vacuum sintering.

Example 1: the A of zhuzhou, hunan province city CEMENTED CARBIDE PRODUCTION producer, the ultrafine gain size mould that the ultrafine WC powder that contains grain growth inhibitor Cr and V that uses us to produce is produced, its life-span is 1.5 times of ordinary rigid alloy mold.

Example 2: the B of zhuzhou, hunan province city company, the ultrafine WC powder that contains grain growth inhibitor Cr and V that uses us to produce is produced hart metal product, and its life-span is 1.6 times of usual prodn.

Example 3: after the ultrafine WC powder that contains grain growth inhibitor Cr and V that the C of Changsha City, Hunan Province company uses us to produce sprayed, coating was fine and close more, and performance is excellent more.

The technology of preparing of the ultrafine WC powder that contains grain growth inhibitor Cr and V that the present invention relates to, working method is simple, processing ease.Product of the present invention is compared with domestic existing product, and facility investment is less, and production cost is lower slightly, and used starting material can not damage operator.

According to technology of the present invention, and, can reach technical indicator provided by the present invention according to method of manufacture operation enforcement of the present invention.

Claims

One kind through mix trace element as additive to suppress grain growth, use the direct reduction and carbonization of APT and prepare the production technology and the technology of ultrafine WC powder.
2. according to the production technology and the technology of the said product of claim 1, it is characterized in that: 1) use the direct reduction and carbonization of APT and prepare the production technology and the technology of ultrafine WC powder; 2) add and the micro-special methods of regulation and control; 3) control of carbon content.
3. ultrafine WC powder production technology and the technology that contains grain growth inhibitor Cr and V according to claim 1, its corresponding production equipment comprises: 1) conversion unit; 2) GK-2B high temperature dispersing furnace; 3) molybdenum wire furnace; 4) graphite burns boat; 5) baking oven; 6) 101 shaped steel iron carbometers; 7) SE-03 type surface apertures appearance; 8) Vacuum Packaging Machine.
4. preparation according to claim 1 contains ultrafine WC powder prescription and production technology and the technology of grain growth inhibitor Cr and V; It is characterized in that: 1) production technique of the present invention is simple; Starting material wide material sources, with low cost obviously improve the economic benefit that the ultrafine WC powder is produced; 2) use the ultrafine WC powder that contains grain growth inhibitor Cr and V of the present invention can produce high-quality ultrafine gain size component, improve the quality product and the economic benefit of manufacturer.